In Chapter 1, we saw that learning and survival are closely related. In general, classical conditioning allows organisms to learn which stimuli signal events conducive to survival and which stimuli signal events detrimental to survival. Once these signals are learned, instrumental and operant conditioning allow organisms to learn appropriate reactions to those signals. Although associationistic theories such as Pavlov’s clearly relate to survival, it was the functionalistic theories, such as those of Thorndike and Hull, that featured evolutionary theory in their explanations of learning. It is also possible to explore the relationship between unlearned behavior and survival. During the heyday of behaviorism, ethologists were stressing the importance of species-specific (unlearned) behavior for survival. They included Karl von Frisch (1886–1982), Konrad Lorenz (1903–1989), and Nikolaas Tinbergen (1907–1988), all of whom shared the 1973 Nobel Prize in biology. Typically ethologists studied a specific category of behavior (such as aggression, migration, communication, or territoriality) in an animal’s natural environment and attempted to explain that behavior in terms of evolutionary 416theory. As we will see, the methods advocated by the ethologists are reflected in the work of William Timberlake and his colleagues (Timberlake, 1997, 1999, 2001, 2002; Timberlake & Lucas, 1989; Timberlake & Silva, 1995), who advocate “animal-centered biological behaviorism,” an approach that synthesizes biological, evolutionary, and physiological understandings of specific categories of behavior as they occur in a natural environment. The ethologists created an awareness that a complete understanding of behavior must take into consideration both learned and unlearned tendencies. This awareness paved the way for significant modifications in behaviorist theory that we discuss throughout this chapter.